Problems Investigating the Causes of Disease
• Specific agent might not be known • Location of agent release might not be known • Signs and symptoms might not differentiate disease • More than one agent might be used • Time of agent release might not be known • Latency period might not be known • Latency is not the same for all Animal

Conducting a Field Investigation
• When possible, collect information that describes:
– When people became ill – Where they acquired the disease – Characteristics of the people

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Conducting a Field Investigation
• When descriptive information does not readily indicate risk factors, analytical methods will be required:
– Determining rates and comparing them
• Comparing ill and well or • Comparing exposed and unexposed

– Most analysis should be done in the field

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Steps in Conducting a Field Investigation of a Bioterrorist Event
• Determine if there is an increase in the occurrence of disease • Confirm the diagnosis of disease • Determine definition of a case • Analyze the data in terms of time, place, and person • Determine who is at risk for becoming ill
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Steps in Conducting a Field Investigation of a Bioterrorist Event
• Develop an hypothesis that explains the specific exposure that caused disease • Test hypothesis using statistics • Compare hypothesis with known facts • Execute control and prevention measures • Plan a more systematic study 36

Determine If There Is an Increase in the Occurrence of Disease
• Initial indication of an increase might be syndromic only • Might need to check hospital and clinic records for increase in symptoms • Might need to telephone a sample of physicians • Might require a rapid community survey • Might be difficult to distinguish between a disease outbreak related to bioterrorism and one from other causes
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Confirm the Diagnosis of Disease
• Frequently requires laboratory techniques • Can not always wait for confirmation before starting treatment and prophylaxis • Might only require laboratory confirmation of first few cases before relying solely on signs and symptoms
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Determine Definition of a Case
• Use signs and symptoms or simple, rapid laboratory techniques • At this point, more important to include all possible cases (high sensitivity) • Use simple case definition to initiate immediate treatment

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Analyze the Data in Terms of Time, Place, and Person to Determine Who is at Risk
• When did patients first start becoming ill • Where were they when they became ill • What were their activities prior to becoming ill and where were they performing these activities

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Explains the Specific Exposure That Caused Disease
• The origin of the specific exposure might not be obvious • Can be the most challenging aspect of the investigation

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Test Hypothesis Using Statistics
• Statistics provide a set of tools that help an epidemiologist reduce the role of chance in hypothesis testing • Statistics can not substitute for an epidemiologists’ review of all the evidence before he decides on an intervention plan

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Compare Hypothesis With Known Facts
• Is the hypothesis in agreement with laboratory, clinical, and other epidemiological evidence • Might need to consult other scientific disciplines (e.g. Medicine, Biology, Environmental Science, Laboratory Science)

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Execute Control and Prevention Measures
• Important to get to this step as quickly as possible, particularly in a case of a highly lethal agent • Sometimes must make decisions that rely on incomplete information • These decisions must be continually reviewed as new information is obtained
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Plan a More Systematic Study
• As control measures are initiated, additional questions will arise that will require additional studies • These studies should use the most applicable epidemiological study methods available

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Prepare a Written Report
• A document for action • A record of performance • A document for potential medical/legal issues • A systematic review of the investigational methods that might suggest additional analysis • A document that will help others investigate and control future bioterrorist attacks
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